Processes for the reclaiming of rubber and for the production of hard rubber products and the like, and the products thereof



F. SVERDRUP VwrPROCESSESFQRHTHE RECLAIMING OF RUBBER AND FOR THE PRODUCTIONV OF HARD RUBBER` ERQDUCTS AND THE LIKE, AND THE PRODUCTS THEREOF *Y Y A 2 Sheets-Sheet 1` Filed June 11, 1956 .Qumw wh.

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` l v l-NVENTOR 50W/WD F .Sl/PQRUP ATTORNEY 2 Sheets-Sheet 2 INVENTOR ATTORNEY 5706/( TEMPEA//EE .-gxA/wa /2 f EXAM/15 /9 F. SVERDRUP FIG. 2.

PROCESSES FOR THE RECLAIMING OF RUBBER AND FOR THE PRODUCTION OF HARD RUBBER PRODUCTS AND THE LIKE, AND THE PRODUCTS THEREOF MLD TEMPEA l/EE Oct. 15, 1957 Filed June ll, 1956 0569555 FA//PEN//E/r BY V//-7r EDWARD E' 5 VE EDEL/P mf United States attentA Office 2,809,944 ?atented Get. i5, 1957 PROCESSES FOR THE RECLAllt/ING F RUBBER AND FR THE PRDUCTN F HARD RUB- BER PRDUCTS AND THE LiKE, ANB THE PRDUCTS THEREF Edvvard F. Sverdrup, Buffalo, N. Y., assigner to U. S.

Rubber Reclaiming Co., Inc., Buffalo, N. Y., a corpo- .ration of New York Application June 11, 1956, Serial No. 590,598

22 Claims. (Cl. S260-2.3)

"This invention relates to processes for reclaiming This application is a continuation-in-part of my cojpending applications: Serial No. 313,983, filed October 9,

1952; Serial No. 343,793, filed March 20, 1953; Serial lNo. 381,111, filed September 18, 1953, and Serial No. 446,379, filed July 28, 1954.

There is a great need for improved processes of ret claiming rubber in such a manner that the reclaimed j product may be revulcanized with particular effectiveness.

There is, moreoven a great need in the mechanical With the foregoing and other considerations in View,

the present invention contemplates the reclaiming of rvulcanized rubber by mechanical Working and heat in .the presence of substantial amounts of added free sulfur,

:and the revulcanization of the reclaimed product in the presence of additional sulfur. In this procedure, the

heat facilitates a desirable preliminary cross-linking of the rubber molecules as the added sulfur combines with the rubber, while, at the same time, the mechanical action and heat plasticizes the rubber and maintains it in a plastic condition.

Any of the usual rubbers, e. g., scrap from tiresy and tubes, may be utilized in accordance with the invention. Mention is specifically made of natural rubber and GR-S (BunaS).

For effective results the comminuted vulcanized rubber scrap may be mixed with sulfur and reclaimed in an extrusion plasticator at elevated temperature in the range 300 F. to 500 F., and mechanically Worked during reclaiming, as by forcing the material toward and thru a restricted orifice using a screw impeller.

Effective results are secured when from about 2.5%

to about 20% of sulfur is employed With respect to the vulcanized rubber scrap. In standard practice, a percentage of from 2.5% to 16% gives excellent results,

but for various purposes, as hereinafter set forth, percentages of sulfur from 2.5% to 5% or more, from 8% to 16%, and from about 6% to about 20% of the Weight from rubber are known, there is still great need for materialshaving particular properties, and the invention contemplates the reclaiming of vulcanized rubber in such a manner as to produce such materials. In certain instances, specific resins are included for certain specific purposes. Altho Vnatural and synthetic rubbers-sometim-es referred to as elastomersare plastics in the broader sense of the word, I reserve that Word herein for the resinous polymer materials other than such elastomers, since, as above indicated, there is a great need in the mechanical arts for hard, tough, non-metallic materials of the rigid plastic type; and there is also a Wide need in the electrical arts for materials of such character which have good electrical insulating properties; and there is also a particular need for such materials which are less expensive than the accepted rigid plastics such as nylon, saran, and vinyl chloride copolymers.

In various of its more specific aspects, accordingly, the invention contemplates the provision of improved processes for the formation of products of the nature abovev indicated from vulcanized rubber scrap and thermosetting phenol-formaldehyde resins, and the provision of such products. I have found that this can be done most effectively by mixing such a resin with vulcanized rubber and reclaiming the rubber by plasticizing the materials in admixture by a joint working at a temperature within the rubber-reclaiming range. Pursuant to the invention, the reclaim may thereafter be cured by being subjected to vulcanizing conditions. Y

For effective results, the Working should be against resistance as by working the material toward and forcing it thru a restricted orifice by a screw impeller.A An effective temperature range for the Working is 300 F. to 500 F., and a preferred range .is from 325 F. to 475 VF. The rubber molecules are broken down by the working action, and are cross-linked with the molecules of the plastic, the two materials being thus integrally unified and transformed into a new and different material.

The composition m-ay be further cured by subsequent treatment if desired. An effective method of cure is that used in vulcanizing hard rubber such, for example, as that hereinafter set forth, and in general by a method employing fro-m about 25 parts to about 47 parts of sulfur per parts of rubber, as hydrocarbon.

Effective results are secured, for example, when 35% by weight or less of the uncured resinous material is mixed with 65% of comminuted vulcanized rubber. Generally good results, and best results in most instances, are obtained when the plastic is in the proportion range from 5% to 15% of the vulcanized rubber. VMaterials. which have given effective results are thermosetting phenol-formaldehyde resins and nylon.

Altho products of the reclaiming of vulcanized rubber in the presence of thermcsetting phenol-formaldehyde resins may be obtained Without the addition of sulfur, highly effective results are obtained when from 2.5% to 5% or more of sulfur (with respect to the rubber scrap) is included in the mix which is subjected to working and plasticizing action. Best results have been obtained with from 3% to 4% of sulfur. The presence of sulfur greatly improves the molding characteristics of the composition and improves and facilitates the formation of a final hard-rubber-like product.

The process may be carried out in a screw plasticator such, for example, as that exemplified in Patent 2,653,- 915 to Joseph C. Elgin and me.

The use of a plasticizer for the resinous material famay be used. Among them are dioctyl phthalate, dibutyl phthalate, and dibutyl sebacate.

The vulcanized rubber scrap and the resinous material may also be treated in other types of apparatus adapted for rubber-reclaiming, e. g., a Banbury or a Baker Perkins mixer.

Pursuant to the invention there may be effectively and inexpensively produced a molding composition ofexceptional quality. This likewiselhas a greatly reduced tendency toward blastering, and an improved gloss.l

An Vadditional advantage of the use of the thermosetting phenol formaldehyde resins of the, present invention is that scrap rubberV may be reclaimed at the same time thatV Ythe`v'ulcanized material andthey resinousV material undergo a thorough mixing. The resin, indeed, seryesto replace muchiof the reclaiming oils normally usedin reclaimingfope'rations. A

There are certain instances, moreover, wherein vulcanized4 rubberA be mixedwith nylon (a longchain syn-v thetic polymeric amide material which hasA recurring amide groupsV asf a'n integral 'part of the mainl polymer chain)' and with sulfur and the'vmixture subjected tomechanical working and heat to reclaim the rubberl and; to provide' a vproduct which caribe vulcanized in; the presenceof'a'dditional sulfur to providey a hard insulating matril.. "Certain, of the vulcanizable products thusA produced can ber'nilled into asniooth 'iiat sheet which, when cured,

will produce'a hardfrubher of exceptionally high elongation withlittle', if any, reductionfin tensile. The percent elongation for rubbers having a tensileof from live to six thousand has, in the past, tended to run from one-"half of onfelpeltito one percent.

VTheseproducts likewise have a greatly reduced tendency toward blistering, and an improved gloss.

`A n additional advantage is that scrap rubber. may bel reclaimed'at 'thesame time that the vulcanized material andthe 'nylon'undergo a thorough mixing. The nylon, indeed, serves'to'replace much of the reclaiming oils normallyuse`d in reclaiming operations.

`For lriiost'eife'ctive"results, the workingl should be against resistancea's by working the material toward' and forcing it through a restricted orice by a screw irnp'eller,

as in'Pater'it 2,653,915 to Joseph C. Elgin and me. An etfectivetempe'rature range for the lworking is 300 F, to 500 F'and,a,preferred range is -from 325 F. to 475 F.

The`composition may be further cured .by subsequent treatment if desired, to produce hard, tough materials iof the rigid'plastic type having good insulating properties. Anetfective 'method ofcure is that used in"vulcanizing hard rubber, such', for Vexample,ias that hereinafter set forth, oiothermetho'demploying from about 25 'parts to` about'47 parts of Sulfur 'per' l100 parts of rubber hydrocarbon.

Effective results are secured, for example, when -35% by weight or less of'iinely'divided nylon is mixed withA 65 %"of`c`omrninu'atel vulcanized rubber scrap. l VIngen-l eral, good results are obtained when5% or more of nylon orother'material is used withrespect to a vulcanized rubberA scrap. YFrom 2.5 %`f to 5% or more of sulfur respect tothe vulcanized rubbe'rscrap) is included 'in the mix prior toY its final working.

of a final hard-rubberlikeproduct.

In crtainof its aspects, the invention contemplates the productionof a reclaimed rubber product which can be used eieetively either in dust formorotherwise in, the

hard-rubberproducts,'hard rubber is ground to a dust and serves to prevent gassing when cornpcmndedl and cured with raw rubber, sulfur, and otherY ingredients. Pursuant to the present invention, a reclaimed lproduct is provided which is usable to replace some or allv oflthe,

y Bestvresults have beenV obtained with from 3% to 4% of sulfur. The presence Y of sulfur greatly improves the molding characteristicsyof the composition and improvesand'facilitiesthe'formationV hard rubber dust in such formulations. Highly effective results for such purposes are obtained when scrap vulcanized rubber is reclaimed by working the same in the presence of a high quantity of added sulfur. The reclaim, particularly when formed with higher amounts of sulfur, tends to be fairly hard, and can thus be easily ground or otherwise broken up into pellet or powder form. Whether or not broken up, the material is thereafter vulcanized, with or without other vulcanizable materials, in the presence of additional sulfur to provide molded and other vulcanized products. When used as a substitute for hard rubber dust, it not only tends to prevent gassing, but is advantageous because it is particularly easy to work on a mill and to disperse in the raw polymer.

The reclaimed product ma for example, be used in extruded or slab form. It may also be used in pellet or powder form with or without additional sulfur and other compounding ingredients, and in` this Vform mayi be` ernployed` as a molding powder from which molded materials may be formed, For the purpose of providing a substitute for hard rubber dust, the quantity of sulfur should'ybe from 6% to 20% by weight of whole tire scrap, e. g., from 12% to 40% by weight of the rubbery hydrocarbon content of the scrap, the term hydrocarbon being used in its usual sense in the rubber industry to include rubbery hydrocarbon material with which sulfur has been combined, as wellas uncombined rubbery hydrocarbon. Preferably, from about 8% to about 16% (based on the weight of whole tire scrap) of added sulfur is employed. For the purpose of making superior cured products from the reclaim itself by revulcanizing with additional sulfur, the vulcanized rubber may be reclaimed with from about 6% to about 15% of added sulfur. For purposes of use asl amoldingpowder, from 6% to 20% may be most effectively used VvEffective results maybe` securedby reclaiming 1n a plasticator such asset forth inPatent 2,653,915 issued to Joseph C.v Elgin and me, at proeeslsI temperatures of from 300'F. to 500 F.

The working of the scrap inhibits the bringing about of a conditionwherein the rubber molecules are so crosslinked by the sulfurl molecules as to provide a highly vulcanized or hard-rubber product, T he added sulfur is combined withtherubberwithout excessive cross-linking. The.y reclaimed scrap, iny spite of relatively low Mooney tigures, i. e., less than 100, contains less than three-quarters of.one percent of f ree sulfur.

Tire scrap formsY a readily available source. of used vulcanized rubbery material-for reclaiming according to the invention. Tires formed of various mixtures. of1natural rubber and GR-S, such as used on automobiles and airplanes, may be satisfactorily reclaimed, as may tires formed of,V natural rubber, of -GR-S, or of other types of rubbers or mixtures thereof as used and usable in tires; and such a vulcanized rubber. or a mixture of rubbers may, of course, beremployed whether ornot embodied in a tire.

There may be includedin the mix various resinous materials, fillers, etc., as required in a particular case. The invention accordingly comprisesthe several steps and the relation and order of one or more ofsuch steps with respectgto each of the othersand thek products possessing thevfeatures and properties. whichare exemplified in the following detailed disclosure, and the scopeofthe application ofwhich will be indicated in the claims.

Fora. fullenunderstandngof thenature and objects of theinvention, referenceshould be hadvto the following detailed description takeny in connectionwith the accom-r panying drawings, in which:

Figure l shows exothermic heatcurves kduring the curing stepsof certainof the examples; and

Fig. 2 shows ,the..rate. of temperature rise l,duringthe E a also,` certain modifications and alternatives, it should be understood that these are not intended to be exhaustive or to be limiting of the invention. On lthe contrary, these illustrations and the explanations herein are .given in order to acquaint others skilled in-the artwith this invention and the principles thereof and a suitable manner of its application in practical use, so that others skilled in the art may be enabled to modify the invention and to adapt it and apply it in numerous forms, each as may be best suited to the requirement of a particular use.

Example 1 hydrated lime, and 3 parts of an accelerator (e. g., a reaction product of butyraldehyde and butylidene aniline), and curled in a mold for 20 minutes at 338 F., an excellent hard-rubber product excellently molded was obtained. The cured product had a tensile strength of 3601 pounds per square inch, an elongation of 3.4% and a Shore D hardness of 86.

Example 2 100 parts of 30-mesh whole tire crumb were mixed with 3.0 parts of pulverized sulfur, 5.0 parts of petroleum resin andA 3.75 parts of a commercial plasticizer as set forth above or in Example 4 below, and passed thru a 3 screw plasticator (as above) rotating at 60 R. P. M. The jacket temperature of the machine was 310 F. The resulting material was then refined once on a laboratory reliner.

When 500 parts of the refined material were compounded with 70 parts of sulfur, 28 parts of chemically hydrated lime, and 3 parts of an accelerator (a reaction product of butyraldehyde and butylidene aniline) and cured for 20 minutes at 338 F., an excellent hard rubber product was obtained.

The cured product had a tensile strength of 3657 pounds per square inch, an elongation of 4.8% and a Shore fD hardness of 86.

Example 3 100 parts of 30-mesh Whole tire crumb were mixed with 15.0 parts of pulverized sulfur and 5.0 parts of petroleum resin and passed thru a 3" screw plasticator (as above), at a thruput of 30 pounds per hour. The jacket temperature of the machine was 309 F. The resulting ymaterial was then refined once on a laboratory reliner.

When 500 parts of the refined material were cornpounded with 30 parts of sulfur, 28 parts of chemically hydrated lime, and 3 parts of an accelerator (e. g., a reaction product of butyraldehyde andbutylidene aniline) and cured for 20 minutes at 338 F., an excellently molded hard-rubber product was obtained. The cured rubber had a tensile strength of 3183 pounds per square inch, an elongation of 1.8% and a Shore D hardness of 88.

Example 4 100 parts of 30-mesh whole tire crumb were mixed with 6.25 parts of a thermosetting phenolformaldehyde Mooney Viscosity ML/212/5-1-(a large rotor Mooneyj operated at 212 F. for 5 minutes following a one-minute warming up time) of 54.

When 500 parts of the resulting product are'cornpounded with 70 partsof sulfur, 28 parts of chemically hydrated lime and 3.0 parts of accelerator (reaction prod-l i uct of butyraldehyde and butylidene aniline), and cured for 20 min. at 338 F., a hard product with excellent molding properties, and a Shore D hardness of 87, v

is obtained. The tensile and elongation are 4750 pounds per square inch and 2.6% respectively.

Example 5 100 parts of 12-mesh black inner tubes were mixed With 6.25 parts of thermosetting phenol-formaldehyde resin, 3.75 parts of plasticizer therefor, and 5.00 parts of pulverized sulfur and passed thru the 3 screw plasticator whose jacket temperature is 307 F. The process temperature is 350 F. The amps consumed at 440 volts is 15.7, and good extrusion is obtainedwith l The Mooney viscosity n a rate of approximately 74#/hr. ML/ 212/ 5-1 of the extruded product was 30.

500 parts ofthe product, when mixed with 70 parts of sulfur, 28 parts of the lime and 3.0 parts of accelerator (reactionproduct of butyraldehyde and butylidene 100 parts of 30-mesh whole tire crumb were-mixed with 6.25 parts of a thermosetting phenolformaldehyde resin, and 3.75 parts of plasticizer therefor, and passed thru the 3 screw plasticator whose jacket temperature was 300 F. The process temperature was 310 F., and a rate of 28#/hr. was obtained. The amperage was 11.2 amps at 440 volts. The extrusion of this material was good, and the material has a Mooney viscosity, ML/212/5-1, of 35.

200 parts of the product, when mixed with 35 parts of sulfur, 9 parts of the lime, and 0.9 parts of the accelerator, and cured for 30 minutes at 338 F., gives l a hard rubber product with a Shore D hardness of 87. The tensile was 5195 p. s. i. and the elongation 3.1%. The molding characteristics of this product were, however, not as good as the material with the sulfur added to the plasticator mix.

Example 7 100 parts of thirty-mesh standard whole-tire scrap A- (fiber-free-from tires which originally contained cotton fabric) were blended in a mixer with 6 parts of molding powder formed from nylon having an extrusion temperature of from 428450 F. V(FM 3606), 0.4 part of dixylyl disullides, 1.3 parts of petroleum oil, 12 parts of petroleum resin, 3 parts of Whiting, and 5 parts ofl sulfur,'and then passed thru a 3 screw plasticator, as above, having a screw speed of 60 R. P. M., at la rate of 68 pounds per hour, an oil temperature of 349 F., and a process temperature of 318 F.

When the product was compounded, 500 parts of the product with 70 parts of sulfur, 28 parts of lime, and 3 parts of accelerator and cured, a hard-rubber-like product having a tensile strength of 4270 pounds per square inch, an elongation of 3%, and a Shore D hardness of was obtained.

ExampleV 8 parts of thirty-meshv standard whole-tire scrap were blended in a mixer with 8 parts of FM 3606 nylon molding powder, 0.3 part of dixylyl disuliides, 1.5 parts of petroleum oil, 14 parts of petroleum resin, 3 parts of Whiting, and 3 parts of sulfur, and then passed thru a The tensile and elongation Vare 3screw plasticator, aslabovve, having a screw lspeed of,

temperature of 296 F., .and a processutemper'ature of 349 Whencompounded (500 partswith70parts of sulfur, 28 parts of limeand 3 parts of accelerator) and cured, a hard-rubber-like product havinga [tensile lstrength of 391.5 POUIldS `Per Square inch, ,an elongation vf '2.5%; and aShoreDf hardnessvkof ,87 was,(obtained.A

Example 9 100 parts of thirty-meshhstandard whole-tire scrap were blended in a mixer with -8 parts of molding powder formedl from nylon having .an .extrusion temperature of from`42 8, F;-45 0.-Fx, (FM.3606:)^,16.25 `parts offplasticizer. ,and.3 partsofsulfurVand then passed ythrua 3" screwplasticator, as. above, havinga screw. speed of. 60 R. P:M., at `a rate ofi24.poundsnpernhour, a jacket temperature of 354.?. F., and VVa process.tenlperatureof When compounded (500gpartswith 70.;parts of sulfur, 28 parts of lime, and .3 parts ofaccelerator) andcured, a hard-rubber-like, product having, atensile strength l.of

393.0 pounds= per square inch, an elongation of 2.5%.v

and a `Shore,D1hardness.of 84 was obtained.

Example] 0 Y 100 parts Aof thirty-mesh, standardwhole-tire scrap were-blended ina mixerwith 6.25 partsofscrap nylon fabric, 8 parts of petroleum resin,`and 4 parts of. sulfur,

and then passed thru a 3" screw plasticator,as above,

4304` pounds per square inch, E1n-:elongation of 2.7%Y

and a Shore ,.D hardness of 88 vwas obtained.v

- Example 11 100 parts of thirty-mesh standard. whole-tire scrap were blended in a mixer with l0 parts lof scrap nylon fabric, 0.3 part of dixylyl disuldes, l2 vparts of petroleum resin, and 4 parts of sulfur, andthen passed thru a 3" screw plasticaton as. ab0ve having a screw Aspeed of 60 R. P. M., ata rate of about 50 ypounds per hour, a jacket temperature ofv 325fF., and a processitemperatureof 360 F.`

When compounded (500 parts with 65 parts .of sulfur, 28 parts of lime, and 3 parts of accelerator) and cured, a hard-rubber-like product having a tensile strength of 3732 poundsper square inch, an elongation of 2.5% and a Shore D, hardness of 86 was obtained.r

In the following examples, reference to exothermic max. temp. refers to the internal rise in temperature which occurs during the combiningof rubber and sulfur in the vulcanization of rubber to the hard rubber stage, which tends to increase the rate of vulcanizationV above that intended, and which` produces porosity. This exothermic heat is measured for a slab of material plied up,l to ll a cavity the Vdimensions of which are 21/2 x 21/2 x 1/2 inches. This is heated. ina `single rectangular cavity in a steeLmold. The mold is placed in the center of electrically heated platens and shielded from external air currents. v An iron-constantan thermocouple is used to measure the temperature of the mold and an otherl the-temperaturein the centerA of the slab. The couple for measuring the mold temperature is placed midway between the cavity andouter edge and at a point midway between top and bottom edges.` The other couple is placedso that Vthe tip is in the exact center of the slab. These couples are connected intoa Brown electronic .strip recorder, 0600 F., which records the mold andslabtemperatures alternately at 15-second intervals..

The mold consistsv of four steel'plates 12"xv12"'x 1A" thick@ Twogof these jplates are the cover plates, The A otherltwo plates form a split mold'having-.a cavity in;A thel center-which is 21/ 2"x 21/2'f`x 1/2,','dee,p.

The splitV mold permits; insertion of one chrome-plated thermocouple tubeflsL" in diameter into the center of, the cavity and one thermocouple ,into the mold itself.l The tip of the mold thermocouple issituated halfwayj between one edge of the cavity and oneedge of the plate.

The exothermic heat is markedly reduced by the use of vthe present invention. Curves` ofthis nature for certainofthe examplesfare shown-in Fig.- 1. Eyen more significante arethe curves showing the--rate :of rise of temperature during the cure. Curves'ofuthisenaturefori the same examples arel shown in Fig.2.v y

In general, whenetherate ofrise'exeeeds 20 YF'. perA minute in the exothermic; portion of the curve, thev com; pound is not safe to cure-in; thick sections (1/2', or over)-- at the test temperature4 (340 R).

The reference to blow-line 'has todo with the porosity or internal cracks present inr the interior of a piece, of -hard ruhigenafter -curing.' It -isbelieved thatthey' areA causedy by the rapid-generationofgas (H28) caused* by excessive -internal heat` (exothermic heat) which'hasI not been-dissipated rapidly-enough-duringthe curing.

Example. 4 12,

parts of 30-meshn whole-tire scrap (fiber-free) wer e mixedwith, .6 parts of sul.fur,8.0 parts of petroleum resin (PDQf40), and 2 partsofurgum (a modi-` fied .A resin acid, specific. gravity :l.06-1..07, softening .j pointfRing l6r` ,Ball35. lE`.-l45"v F., with-,an acid num-v ber: of 146),- ThisTmixture.waspassedithru Aa 3 plas-y ticator, as setforth in;AFig. 1 ofsaidMPatent 2,653,915' issued to JosephC. Elgin and.me,.=whose;jackettemper ature was 275' F. The process temperature was about., 325,"` F. asmeasuredbya .thermocouple placed about` in the Ecenter of ythe barreland next externally to theliner.A

When the product was press-cured ;20fat `340- F.- in. the following formulation:

Product of.Example l2 100.0 e

Sulfur 11.0 Warner lime 5.6

Aldehyde amine accelerator (A-32) 0.6

Formulation:`

GR- Hard rubber dust Product of Example l2 (in the form of discrete particles such as described in the application .of `Benjamin R. Wendrow, Serial No. 326, 933, tledDecember 19,. 1952 now Patent 2,767,149). Aldehyde amine accelerator Petroleum oil (Circo) Sulfur Exothermic max. temp., F Blow line in exotherlmie piece Molding Cure 20 at 340 F.:

Tensile Elongation.

Hardness Cure 25at 340 F.:

Yes. Very good.

Hardness. Cure 30 at 340 F.:

Tensile Elongation Hardness 9 Example 13 100 parts of 30-mesh whole tire scrap (liber-free) were mixed with 8.0 parts of sulfur, 8.0 parts of petroleum resin (PDO-40), and 2 parts of Turgum-S. p This mixture was passed thru said 3" plasticator whose jacket temperature was 250 F. The process temperature was about 330 F. as measured by a thermocouple placed about in the center of the barrel and next externally toV the liner. 4 l

IWhen the product was press-cured 20 at 340 F. in theufollowing formulation:

Product of Example 13 100.0 Sulfur 10.0 Warner lime 5.6 Aldehyde amine accelerator (Af-32) 0.6

results were obtained. The following table shows the results when the base hydrocarbon was standard GR-S:

Formulation:

GR-S 100.0 Hard rubber dust 100.0 p Product of Example 13 (as in Example 12) 100.0 Aldehyde amineaccelerator (808) 3.0 Petroleum oil (Circo) f 7.0 v Sulfur 45.0 Blow line in exothermic piece Yes Exothermic max. temp., F. 392 F. Molding i Very good Cure 20at 340 F.: Tensile 4150 Elongation 9.7 Shore `D hardness 83 Cure 25 at,340 F.: Tensile 4285 Elongation 4.3 Y AHardness 86 Cure 30 at 340 F.: p

Tensile 5795 Elongation 3.3 Hardness Example 14 i 100 parts of 30mesh whole tire scrap (liber-free) were mixed with parts of sulfur, 8.0 parts of petroleum resin (PDO40), and 2 parts of Turgum-S. This mixture was passed thru said 3" plasticator whose jacket ternperature was 275 F. The process temperature was about 325 F. as measured by a thermocouple p'laced about in the center of the barrel andnext externally to the liner. Y

`The product had a Mooney (vMS/2l2/5-1) viscosity of `6l and a Shore D hardness average of 38.

When the product was press-cured 20 at 340 F. in the following formulation:

Productot'Example 14 100.0 Sulfur 9.0 Warner lime 5.6 Aldehyde amine accelerator (A32) a maximum exothermic heat of 346 F. Was obtained. The tensile strength was 2785#/sq. in. and the elongation 1.6%. The Shore D hardness was 85. f

Whenthe product of Example 14 is used to replace hard rubber dust in a hard rubber formulation, excellent results are obtained. The following table shows the Formnlatonzp Hard rubber dust 100 Product of Example 14 (as in Example 12)-- 100 200. Aldehyde-amine accelerator (808) l 1 3. Petroleum oil (Circo) 7 7. Sulfur 45 55. Blow line in exothermic piece.. Yes Yes. lEaxtlihermie max. temp., F. $10 00.

o ing e 0o er ood. Cure 20 at 340 ry g g Tensile 5,895.

Elongation 5.7 3.7. Hardness 83. Cure 25 at 340 F.:

l Tensile 6,690 5.790. Flnmzatinn 3.0 3.0. Hardness 87 86.

Cure 30' at 340 F.:

Tensile 7,170 6,020. Flnngatnn 3.1-- 3.3. Hardness 86.

1 Example 15 parts of 30-mesh whole tire scrap (fiber-free) were Product of Example l5 100.0 Sulfur 8.2

Warner lime 5.6 Aldehyde amine accelerator (A-32) 0.6

. a maximum exothermicheat of 347 F. was obtained. .The tensile strength was 2330#/sq. in. andthe. elonga tion 1.7%. The Shore D hardness was 86. i

When the product of Example 15 is used to replace hard rubber dust in a hard rubber formulation, excellent results were obtained. The following table shows. the results when the base hydrocarbon was standardvGR-S:

Formulation:

`GR-S 100.0 Hard rubber dust 100.0

Product of Example l5 (in powdered form) 100.0

Aldehyde amine accelerator (808) 3.0

Petroleum oil (Circo) r l7.0

Sulfur Y 45.0 Blow line in exothermi-c piece.` No Exothermic max. temp 394 F. Molding Very good Cure 20' at 340 F.:

Tensile 6140 Elongation 4.3

Shore D hardness L.-- '85 Cure 25 at 340 F.:

Tensile 6370 Elongation 3.3

Shore D hardness 86 Cure 30 at 340 F.:

Tensile `6870 Elongation 3.0

Shore D hardness 8-7 Example I6 100 parts yof 30mesh whole tire scrap (fiber-free) were mixed with 15 parts of sulfur, 8.0 parts of petroleum resin (PDO-40), and 2 parts of Turgum-S. This mixture was passed thru said 3 plasticator whose jacket temperature was 275 F. The process temperature was about 325 F. as measured by a thermocouple placed about inthe center of the barrel and next externally to the liner.`

averagefof184 and --a Shore YD hardnessgof 56. Titlefreeef'l the following formulation: Y

Productfof Example 16;. `100.0 Sulfur 7.0 Warner -lime r 751.6 Aldehyde famine accelerator (A-32 f i 0.6

a maximum exothermic heat of 347 F. was obtained. The tensile vrstrength`-was v 3060#/sq7. in.,` elongatio'n12.0% and the Shore' D' h'ardn'es's w'as`83.

Whe'ntherpro/dutof Example 16 isused^tofre'place hard rubber'dustin a hrdrubber formulation (instead of being used as the source of rubbery hydrocarbon), excellent results are obtained. The following table shows Vthe results when the base'hydrocarbon is standard GR-S:

1Ex vEx- E x- Hard -ample `ample ample Rubber 16 16a 16D Dust Frinulatin: y

" GR-S l -..v 100 1100;..- 100;" 100. Hard rubber dust v 100 1 00 100. Product of Example 16 (in pow- 100 100 200 dered form).

' Y Aldehyde amine accelerator (808)- Petroleum oil (Crco) ulfur Exothermic max. temp., F. Blow line in exothermic piece Molding Cure-20 at 340 F.: l

Tensile l Elongation 3 Hardness-..

Cure 30 at 340 Tensile Elongation.-

' Hardness Cure 454 at 340 F.:

Tensile Elon gatin Hardness Example 17 l100 parts of 30lmeshwholeltire scrap .(fiberfree`) ywere mixed with 16.0 parts of'sulfur, l`2`.'0parts ofpetroleum resin.(PDO-40)", and 3.0 parts of Turgum-S.V This mixture/was passed'thru said'3""'pla`sticator whose jacket temperature was `250`F.VA The process temperature wasl about 300 ras measured by a vthermocoupleV placed -alboutin' the center of thebarrel and next externally to the liner.

The". product of Example 17 did not cure satisfactorily inlthe following test formulation:

Product'of'Example 17 1 100.0 Sulfur 6.6 Warner lime 5.6 A'ldehyde amine accelerator (A432) 0.6

When the product of Example 1'7 is-used to replace hard rubber dustvin Ya hard rubber formulationyexcellent results are obtained. The following table shows the results when'thebas'ehydrocarbon isstanda'rd GIFS:

Formulation:

GR-s 100.0 Hadrubber dust 100.0 -Pduct ofExam'ple17 (in powdered form) 100.0 `"Aldehyde-amineaccelerator!( 808) Y3.0

Petroleum oil (Circo) A `7.0 sulfurA '45.0

BlivI line in 'exothermic piece l No Eitherfnicmax. temp., F --.385

Molding Very good -Cure 30 at 340 F.:

zgan-9,044"

Tensile- Elongation Y Hardness Y Example' 18" partsY of Y 30-rnesh -whole-tire scr-ap -(fiber-free) were mixed with 18:0Y parts of Isulfur, 31f40 'parts'of petroleum resin (PDO-40), and 3.5 partsof Turgum S. This mixture was' passed thru said 3 Ypltsticatorwhose -jacket Stemperature was' v250'F.` The process 'temperature was about 312 as 1"1'ne'a'sured*by 'a `thermocouple vplaced about -in thecenter of'the barrel and'nextexternallyto the liner.' v l The' product vof lExample 1 8; which had a "Mooney (MS/'212541) viscosity v"of "91' tand aShore D hardnessV When the product of Example 18is used to replace hard -rubber dust in a hard rubber-.formulatiom ex- "collent results are obtained. The following table shows the results when the base hydrocarbon is standard GR-S:

Formulation:

Hardrubber-dust r 100.0

100 parts of '3G-mesh whole-tire scrap (ber-free) were mixed with 20 parts of sulfur, 8.0 parts of petroleum resin (PDO-40), and2 parts of Turgum-S. This mix-Y turer was passed vthr'umsaid'l3 plasticator `Whose jacket temperature was 275 F. The process temperature was approximately 330 F. asmeasuredby a thermocouple placed about inthe-.center of therbarrel and nextexternally to the liner.

The particular-product of `Example 19 was too dry and-friabletocompoundlby itself. Y

When -the product of-Example 119 was `used-'to :re-`

place fhard .rubber-dust inhardrubber-f formulations, the

following results were obtained:

Example Example Hard Rub- 19 19a ber Dust Formulation:

GR-S 100 100 100. Hard rubber dust 100 100 Product of Example 19 (in 00 powdered form). Petroleum oil (Circo) Sulfur 45 Aldehyde amine accelerator Blow line in exothermic piece Exothermic max. temp. F-

Fair.

100 parts of 30-mesh fiber-free whole-tire crumb were mixed with 15.0 parts of pulvelized sulfur and 5.0 parts of petroleum resin and passed thru said 3" plasticator as above at a thruput of 30 pounds per hour. The jacket temperature of the machine was 309 F. The resulting material was then refined once on a laboratory rener.

When 500 parts of the rened material were cornpounded with 30 parts of sulfur, 28 parts of chemically hydrated lime, and 3 parts of an accelerator (e. g., a reaction product of butyraldehyde and butylidene aniline), and curved for 20 minutes at 338 F., an excellently molded hard rubbed product was obtained. The cured ruber has a tensile strength of 3183 pounds per square inch, an elongation of 1.8%, and a Shore D hardness of 88.

Example 21 100 parts of 30-mesh liber-free whole-tire scrap were mixed with 15.0 parts of sulfur, 8.0 parts of petroleum resin (PDO-40), and 2.0 parts of Sonastic (softening point 145 F. maximum and 140 F. minimum, acid No. 150 maximum and 146 minimum with a trace of tolueneinsoluble material), 6.25 parts of phenolic resin (Durez 13355-a two-stage resin formed rst as a thermoplatic resin short of formaldehyde and then formed into a thermosetting resin by the addition of hexa during the grinding operation), and 3.75 parts of plasticizer (Durez 50800). This mixture was passed thru said 3" plasticator whose jacket temperature was 250 F. The operating temperaturewas above 300 F.-a reading of 290 F. having been given by a thermocouple about 6" forward of the center of the barrel and next externally to the liner.

When the product was press-cured 20 at 338 F. in the following formulation:

a maximum exothermic heat of 342 F. was obtained. The tensile strength was 2822#/sq. in., the elongation was 0.8% and the Shore D hardness was 88.

To insure most eiective dispersion, the reclaimed product of Examples 12-21 should be compounded as follows pursuant to the invention:

The reclaimed product is rst banded on a tight mill so that a very small bank is formed in the nip. For a 150-gram batch of the reclaimed product, the mill opening is about 0.015" on a 6" x 12" mill, and the roll temperature about 150 F.; then some of the oil normally used in the complete compound, e. g., 15 grams, is slowly added to the reclaimed product, taking care to prevent breaking up the material into bits. Ordinarily just enough of the oil is added to make the reclaimed product smooth and plastic. The remainder of theoil may be added later to the compound in the usual manner. The proper proportion of the reclaimed'product which has been masterbatched with oil is left on the mill and the plasticized new polymer, e. g., GR-S, is fed into the masterbatch on the mill. After cutting back and forth several times, with the mill adjusted for a low bank, the remainder of the compounding ingredients are added.

Since certain changes may be made in the products set forth and in carrying out the above processes, and different embodiments of the invention may be provided without departing from the scope of the invention, it is intended that all matter contained in the above description or shown in the accompanying drawing shall be injecting the soft vulcanized rubber in the presence of the sulfur Ato the continuous kneading action of mechanical workingat a'temperature of from about 300 F. to about 500 F; 'which 'pla icizes the soft vulcanized rubber to reclaim if.

2. A process as set forth in claim 1 wherein not over 16% by Weight of sulfur is mixed with the vulcanized rubber prior to reclaiming.

3. A process as set forth in claim 1 wherein the reclaimed product is converted into discrete particle form mixed in such form with raw rubber, and vulcanized therewith.

4. A process as set forth in claim 1 wherein the vulcanized rubber is mixed with a long-chain synthetic polymeric amide material which has recurring amide groups as an `integral part of the main polymer chain, as well as with sulfur.

5.v A` process as set forth in claim 4 wherein the proportionl ofthe synthetic polymeric amide material with respect to thevulcanized rubber is not more than 35% .y

6; A vulcanizable reclaimed product produced by the process of` claim 4.

7.` A process wherein the product of claim 1 is mixed with raw rubber and vulcanized in the presence of additional sulfuri-` 8. A process as set forth in claim 7 wherein oil is milled in prior to the mixing with the raw rubber, and the additional sulfur is added after the mixing with the raw rubber.

9. The process of transforming soft vulcanized rubber into a plastic reclaimed product vulcanizable into a hard product which comprises mixing the soft vulcanized rubber with from about 2.5% to about 5% by Weight of sulfur and Vreclaiming by subjecting it to the continuous kneading action of mechanical working at a temperature of from 300 F. to 500 F. which plasticizes the soft vulcanized rubber to reclaim it.

10. The process of producing a hard product which comprises mixing soft vulcanized rubber with from about 2.5 to about 20% by weight of sulfur, and subjecting the soft vulcanized rubber in the presence of the sulfur to the continuous kneading action of mechanical working at a temperature of from 300 F. to 500 F., which plasticizes the soft vulcanized rubber to reclaim it and thereafter vulcanizing in the presence of additional sulfur in an amount which when added to the amount of sulfur mixed with the vulcanized rubber will bear the relationship to the rubber hydrocarbon present of from 25 to 47 parts of sulfur per parts of rubber hydrocarbon.

l1. A process as set forth in claim 10 wherein the soft vulcanized rubber is mixed with a long-chain synthetic polymeric amide material which has recurring amide groups as an integral part of the main polymer chain, as well as with sulfur.

12. The process of producing a rubber-like product which comprises mixing Vvulcanized' rubber scrap1and-b'etween 5% and 15% of thermosettingphenol formaldehyde resin, reclaiming the rubber bya working and plasticizing action at a temperature of from about 300 F. to about 500 F., and curing the resultingcomposition.

13. Aprocess as set forth in claim l2^wherein the curing takes place in thepresence of from about 25 parts to about 47 parts of sulfur. per 100 parts of rubber'hydrocarbon.

14. A product produced-by the process of claim '13.

15. The process of ,producing.afvrubber-like product which comprisesmixing at least 65 parts'fby w'eightofV vulcanized rubberscra'p'andfnot over 35 parts of* thermo-V 16. The processfof producing'a composition whichis moldable into a rubber-like product which comprises'mixing vulcanized rubber scrapy and thermosetting phenol# formaldehyderesin andreclaimingthe rubber by subjecting the mixture' to a Working and'plasticizing action at a temperature of from about 300 F. to about 500F.

17. A..process as set forth in claim 16 wherein there is included' inthe mix atleast- 2.5% of sulfur with respect to the weight of the vulcanized rubber scrap.

18. A product produced by the process of claim 16.

19. A process'aslset forthin claim l16whereinthe proportionfof said resin is not more than 35 Yparts to 65 parts by weight of vulcanized rubber scrap.

20. A"process as"set.forth'`in claim 19 wherein there is included'in'the mix from`3% 'to 4% ofsulfur with respect to the vulcanizcd'rubber scrap.

21. yA fproduct;produced*by the vprocess of claim 17.

22. The process of forming a molding powder which comprises mixing scrap soft'vulcanized rubber with from 6% to 20% by weight of added sulfur, subjecting the soft vulcanized rubber in the 'presence of the sulfur to the continuous kne'ading--action of mechanical working at a temperature Yof'froin about 300 F. to'about500 F. which plasticizes vtheisoft vulcanized-rubber toreclairn'it, and converting the reclaim into discrete particle form.

References Cited in the le of this patent UNITED STATES PATENTS 838,419 Karavadine Dec. 11, 1906 

1. THE PROCESS OF RECLAIMING VULCANIZED RUBBER WHICH COMPRISES MIXING SOFT VULCANIZED RUBBER WITH FROM ABOUT 2.5% TO ABOUT 20% BY WEIGHT OF FREE SULFUR, AND SUBJECTING THE SOFT VULCANIZED RUBBER IN THE PRESENCE OF THE SULFUR TO THE CONTINUOUS KNEADING ACTION OF MECHANICAL WORKING AT A TEMPERATURE OF FROM ABOUT 300*F. TO ABOUT 500*F. WHICH PLASTICIZES THE SOFT VULCANIZED RUBBER TO RECLAIM IT. 